DNA fragments can be joined together by using

Question

Question

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Answer 1

Correct Answer: DNA Ligase

Rationale:

DNA ligase is an essential enzyme used in molecular biology to join DNA fragments together. It works by catalyzing the formation of a phosphodiester bond between the 3' hydroxyl end of one nucleotide and the 5' phosphate end of another. This enzyme is crucial in various processes such as DNA replication, repair, and recombination.
During DNA replication, DNA ligase plays a vital role in sealing nicks in the sugar-phosphate backbone of the DNA. It is also used extensively in genetic engineering and cloning to insert DNA fragments into plasmids or other vectors.

Explanation of Other Options:

Restriction Endonuclease

Rationale: Restriction endonucleases are enzymes that cut DNA at specific recognition sequences. They are used to create DNA fragments with sticky or blunt ends for cloning or other molecular biology applications. However, they do not join DNA fragments together; their primary function is to cleave DNA.

Okazaki Fragments

Rationale: Okazaki fragments are short sequences of DNA nucleotides that are synthesized discontinuously on the lagging strand during DNA replication. They are later joined together by DNA ligase. Okazaki fragments themselves are not enzymes and cannot join DNA fragments.

DNA Helicase

Rationale: DNA helicase is an enzyme that unwinds the DNA double helix during DNA replication, allowing each strand to be copied. It breaks the hydrogen bonds between the base pairs, but it does not join DNA fragments together.

Conclusion:

Among the given options, DNA ligase is the correct enzyme that joins DNA fragments together. It plays a critical role in DNA replication, repair, and molecular cloning techniques by sealing nicks in the DNA backbone, ensuring the integrity and continuity of the DNA molecule.